The compound represented by the following general formula (1) is expected to be a highly safe pharmaceutical compound having an anti-inflammatory action based on the excellent VLA-4 inhibitory action (International Publication WO2002/053534).

Compound (12) [a compound wherein R1 is hydrogen atom in Compound (VI-trans)] is an important intermediate in producing such Compound (1).

This compound has been synthesized by forming methylether structure at primary hydroxy group of hydroxypurine by Mitsunobu reaction; converting carboxylic acid moiety to hydroxymethyl group; introducing benzoic acid unit; reducing benzene ring of the benzoic acid moiety to obtain 1,4-cyclohexanecarboxylic acid ester comprising predominantly cis form; and conducting isomerization reaction via enolate (International Publication WO2002/053534).
Mitsunobu reaction, however, requires use of an azo reagent which is associated with the risk of explosion, and a large amount of unnecessary products are generated deriving from the reagents used in the reaction, requiring additional purification for the removal of such products. Accordingly, this method has many drawbacks for use in a mass synthesis. Furthermore, the reduction of benzene ring produces predominantly cis form product, and the step of isomerization was necessary to obtain the trans form. However, since the step of isomerization reaction required long time, hydrolysis of the ester occurred under the isomerization reaction conditions to produce a carboxylic acid as a byproduct. Accordingly, re-esterification of the carboxylic acid was necessary.
As described above, the conventional process required multiple Mitsunobu reaction step for the production of the Compound (1) rendering the process unfit for the large scale production. Furthermore, generation of the byproduct by the hydrolysis during the isomerization reaction also leaves much to be improved for use in an industrial production process.